ARCHER, ON DESMIDIACEJi. 229 



Now it is, I apprehend, not a little worthy of remark that 

 the swarming, active, disintegrated granules disassociated 

 from the rest of the endochrome, described above as of fre- 

 quent occurrence, are met with at this stage, as well as 

 frequently at the stage indicated by Fig. 1, when the lateral 

 tube first appears as a mere tubercle ; and, moreover, presents 

 precisely the same appearance and conditions that other 

 specimens of this species (D. Ehrenbergii) on the same slide 

 exhibit, but which are not destined to undergo the other 

 changes here described. Further, numerous other species, 

 which occurred in the same gathering, presented similar 

 examples of the molecular swarming movement ; for example, 

 Docidium clavatum, Gonatozyon Rcdfsii, various Cosmaria, 

 &c. But I think it is not less equally worthy of remark, that 

 other specimens undergoing the peculiar development, of 

 which the production of the lateral tube is a stage, did not 

 indicate any molecular or swarming movement of the 

 minute granules of the endochrome — that in the terminal 

 spaces, of course, excepted. On the whole, then, it does not 

 appear to me that these swarming granules had anything 

 specially to do with the production of the very different motile 

 bodies now to be described. 



I have before stated that the endochrome near the base of 

 each segment, and filling the lateral tubes, becomes very 

 finely granular ; it next becomes segmented into a definite 

 number of rounded portions, or "gonidia." I was never 

 able to count them exactly, but I suppose they were not less 

 than twenty, nor over fifty ; nor did the fact of there being 

 either two or three lateral tubes developed seem to indicate 

 any very great addition to the number of these bodies. That 

 portion of the endochrome not thus transformed into gonidia 

 lying beyond them, and extending to the ends of the segments, 

 by this time loses its normal character, and seems to become 

 drawn into detached bands or strings, with a few free 

 granules, and the terminal cavity, with the active particles, 

 becomes lost. The gonidia lately formed at the middle of 

 the frond have now emerged through the opened apex of the 

 lateral tube, and remain clustered together in a mass very 

 much like a bunch of grapes, the clusters becoming, by 

 degrees, larger and larger, mitil all the gonidia make their 

 exit through the tube, and each adds its quota to the group 

 (Fig. 3) . The same is the case when there are two or three 

 tubes, the only difference being that a fewer number, but 

 generally about equal, make their way through each (Fig. 4) . 

 Meantime, the unused endochrome, which had become drawn 

 into detached strings, now loses its bright-green colour, 



